Various proposals have been made for the manufacture of capacitor by photoprocessing techniques.
High capacitance normally involves the use of very thin dielectric layers. Photoprocessing involves the repeated handling of the layers which can damage or interrupt thin layers. Hence, heretofore, it has not been possible to consistently obtain high quality capacitors of high capacity by photoprocessing techniques.
The product of Yates U.S. Pat. No. 3,998,601 is characterized by several problems. The microthin layer of 2 to 12 microns has been found in many cases to contain pinholes which render the laminate unsuited for its intended purpose. Yet another problem in the practice of Yates is that the microthin copper is often badly stained or marked. In contrast thereto, we have found that by adhering to a certain combination of conditions in the bath, this serious problem can quite surprisingly be solved and a reproducible commercial laminate useful in the production of capacitors can be obtained.
The present invention has solved a long-standing problem in the art and it is to be expected that this invention will be rapidly adopted by those skilled in the art.